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Citrus growers facing fears of dread disease

An orange tree infected with citrus greening yields misshapen fruit, left,
and yellow veining, both classic symptoms of the disease.

LAKELAND LEDGER ARCHIVE / 2008 / MICHAEL WILSON

By KEVIN BOUFFARD Lakeland Ledger

Published: Friday, March 8, 2013 at 1:00 a.m.

Last Modified: Thursday, March 7, 2013 at 8:24 p.m.

LAKE ALFRED - A standing-room-only crowd of more than 400 growers at the Citrus Research and Education Center this week testified to the increasingly desperate search for new tools to control the deadly citrus greening disease sweeping across Florida.

"It speaks volumes to the concern over citrus greening and wanting to hear something positive," said Harold Browning, chief operating officer at the Citrus Research and Development Foundation Inc., the lead agency in the research effort against greening and a seminar sponsor along with Lakeland-based growers organization, the Florida Citrus Mutual.

Some local growers did not get what they wanted to hear.

"I don't know how long we can stay in business," said Gene Paul of Bob Paul Citrus Inc. in Winter Haven, which has about 2,000 grove acres in Highlands and Hendry counties. "This seminar is not invigorating; it's depressing."

Others saw hope for the future.

"We're still supposed to be doing what we're already doing," said Frank Hunt III of Hunt Bros. Inc. in Lake Wales, a family company with about 5,000 acres in Polk and Collier counties. "But we're encouraged for the future."

The growers came to the seminar to hear a summary of scientific presentations given during the International Research Conference on HLB during the week of Feb. 4 in Orlando. Many scientists refer to greening as HLB, the acronym for the disease's Chinese name, huanglongbing, where it originated.

Several participants said they were most excited about nine antimicrobial chemicals that preliminary research shows can counteract or even eliminate the greening bacteria in a citrus tree without any toxic effects to the plant. The chemicals can be sprayed or injected into the tree or root system, Browning said.

Further research over the next year seeks to identify the chemical that work best against the bacteria in Florida conditions. Once identified, the foundation would need a partner willing to pick up the costs of regulatory approval and manufacturing the chemical.

Some of the promising antimicrobials are "lightly regulated" natural substances that should not require extensive regulatory review by state and federal agencies and could be available to growers soon, Browning said.

Others could require several years of regulatory review by federal agencies including the Department of Agriculture, the Federal Trade Commission and the Environmental Protection Agency, he said. The review would also mean millions of dollars more in additional testing.

Growers currently rely on enhanced foliar nutrition, a program of intensive spray fertilizers that replace many of the minor nutrients greening robs from a citrus tree and counteracts the disease's effects, including defoliation and bitter fruit.

But enhanced nutrition does not stop the disease's spread or completely counteract greening effects on the tree or to the fruit, said Steve Futch, a citrus extension agent at the Lake Alfred center.

Research has shown greening affects juice quality, including a "lingering metallic taste," he said. It affects early season Hamlin oranges more than late-season Valencia oranges.

Enhanced nutrition has not successfully counteracted premature fruit drop, which growers have discovered in the 2012-13 season, Futch said.

This season's premature drop of Hamlins was the highest in 43 years.

Michael Rogers, an entomologist at the Lake Alfred center, reported one of the more discouraging findings.

Since greening first surfaced in Florida in 2005, entomologists have focused on controlling the Asian citrus psyllid as the host of the greening bacteria and primary cause of its spread.

Research has found another Florida insect, the striped mealybug, also hosts the greening bacteria and can spread the disease, Rogers said. However, the mealybug does not acquire the bacteria or spread it as efficiently as psyllids.

<p><em>LAKE ALFRED</em> - A standing-room-only crowd of more than 400 growers at the Citrus Research and Education Center this week testified to the increasingly desperate search for new tools to control the deadly citrus greening disease sweeping across Florida.</p><p>"It speaks volumes to the concern over citrus greening and wanting to hear something positive," said Harold Browning, chief operating officer at the Citrus Research and Development Foundation Inc., the lead agency in the research effort against greening and a seminar sponsor along with Lakeland-based growers organization, the Florida Citrus Mutual.</p><p>Some local growers did not get what they wanted to hear.</p><p>"I don't know how long we can stay in business," said Gene Paul of Bob Paul Citrus Inc. in Winter Haven, which has about 2,000 grove acres in Highlands and Hendry counties. "This seminar is not invigorating; it's depressing."</p><p>Others saw hope for the future.</p><p>"We're still supposed to be doing what we're already doing," said Frank Hunt III of Hunt Bros. Inc. in Lake Wales, a family company with about 5,000 acres in Polk and Collier counties. "But we're encouraged for the future."</p><p>The growers came to the seminar to hear a summary of scientific presentations given during the International Research Conference on HLB during the week of Feb. 4 in Orlando. Many scientists refer to greening as HLB, the acronym for the disease's Chinese name, huanglongbing, where it originated.</p><p>Several participants said they were most excited about nine antimicrobial chemicals that preliminary research shows can counteract or even eliminate the greening bacteria in a citrus tree without any toxic effects to the plant. The chemicals can be sprayed or injected into the tree or root system, Browning said.</p><p>Further research over the next year seeks to identify the chemical that work best against the bacteria in Florida conditions. Once identified, the foundation would need a partner willing to pick up the costs of regulatory approval and manufacturing the chemical.</p><p>Some of the promising antimicrobials are "lightly regulated" natural substances that should not require extensive regulatory review by state and federal agencies and could be available to growers soon, Browning said.</p><p>Others could require several years of regulatory review by federal agencies including the Department of Agriculture, the Federal Trade Commission and the Environmental Protection Agency, he said. The review would also mean millions of dollars more in additional testing.</p><p>Growers currently rely on enhanced foliar nutrition, a program of intensive spray fertilizers that replace many of the minor nutrients greening robs from a citrus tree and counteracts the disease's effects, including defoliation and bitter fruit.</p><p>But enhanced nutrition does not stop the disease's spread or completely counteract greening effects on the tree or to the fruit, said Steve Futch, a citrus extension agent at the Lake Alfred center.</p><p>Research has shown greening affects juice quality, including a "lingering metallic taste," he said. It affects early season Hamlin oranges more than late-season Valencia oranges.</p><p>Enhanced nutrition has not successfully counteracted premature fruit drop, which growers have discovered in the 2012-13 season, Futch said.</p><p>This season's premature drop of Hamlins was the highest in 43 years.</p><p>Michael Rogers, an entomologist at the Lake Alfred center, reported one of the more discouraging findings.</p><p>Since greening first surfaced in Florida in 2005, entomologists have focused on controlling the Asian citrus psyllid as the host of the greening bacteria and primary cause of its spread.</p><p>Research has found another Florida insect, the striped mealybug, also hosts the greening bacteria and can spread the disease, Rogers said. However, the mealybug does not acquire the bacteria or spread it as efficiently as psyllids.</p><p>Rogers and Futch agreed the best strategy for controlling greening remains enhanced nutrition combined with regular insecticide spraying to keep psyllid populations down.</p><p><empty></p>